diff --git a/Core/include/ACTS/Tools/CylinderVolumeBuilder.hpp b/Core/include/ACTS/Tools/CylinderVolumeBuilder.hpp
index e79965e0cafdf38e960458a4260ea9b2de3f0dcd..0f5f73a39df6494d6dbc795f08a7cb5ed15ab9de 100644
--- a/Core/include/ACTS/Tools/CylinderVolumeBuilder.hpp
+++ b/Core/include/ACTS/Tools/CylinderVolumeBuilder.hpp
@@ -300,7 +300,7 @@ public:
           wCondition       = Attaching;
           wConditionScreen = "[n attched]";
         }
-        if (pVolumeConfig && pVolumeConfig.zMin < existingVolumeConfig.zMax) {
+        if (pVolumeConfig && pVolumeConfig.zMin > existingVolumeConfig.zMax) {
           pVolumeConfig.attachZ(existingVolumeConfig);
           // will attach the new volume(s)
           wCondition       = Attaching;